Si Etching

RIE  isotropic

Fluorine based process

etch rates: 0.5  -  10 µm/ min

high selectivities

strong loading effect

Courtesy of IMO Wetzlar:
70 µm deep isotropic etch
mask still intact

OPT Application lab:
50 µm deep anisotropic low
temperature etch
for micromechanical devices

Courtesy of Uni Kassel
Si AFM peaks by RIE

Si nanopillars
Courtesy of
The University of Birmingham

RIE anisotropic

mostly Cl/ Br based process

etch rates:  50 - 300 nm/ min

anisotropic profile

good selectivity to SiO₂

OPT Application lab:
1 µm deep anisotropic polySi with HBr for very high selectivities

ICP - RIE

Fluorine based processes

rates: 1 - 20 µm/ min

very high selectivities possible

aspect ratio dependent etching (RIE lag)

OPT Application lab:
50 µm deep anisotropic room temperature etch
for micromechanical devices ("Bosch Process")

OPT application lab:
photonic crystals
5 µm holes etched in Si
with stop on SiO2

OPT application lab:
lenses etched into Si